Machine head for tuning a stringed instrument, especially a guitar or the like

Abstract

A machine head, especially for precision tuning of a guitar string or strings, avoids the slackness between the cog and worm gear drive of the existing design which can give rise to tuning slip and imprecise tuning. The proposed machine head has a spindle to which a string is secured at one end and carries an arm (2a). Adjusting screw (3) cooperates threadingly with an abutment (7) and the end of the adjusting screw bears on the arm whereby rotation of the adjusting screw determines the position of the arm and hence tension in the string.

I claim: 
     
       1. A machine head for fitting to a stringed instrument for tensioning and so tuning up a string, the machine head comprising: a spindle around which the string is passed and to which the string is secured, the spindle having a longitudinal axis;   means mounting the spindle for rotation about the longitudinal axis;   a single arm extending from the spindle; and   screw threaded adjusting means including a threaded member which threadingly engages an abutment and a free end which engages the arm, for displacing the arm and thereby rotating the spindle about its longitudinal axis to pull the string around the spindle and tension the string.   
     
     
       2. A machine head as claimed in claim 1 in which the arm has a curved surface which is tangential to a point of engagement by the free end of the threaded member. 
     
     
       3. A machine head as claimed in claim 1 in which the free end of the threaded member has a curved surface to engage the arm. 
     
     
       4. A machine head as claimed in claim 3 in which the arm is fixedly secured to the spindle. 
     
     
       5. A machine head as claimed in claim 4 in which the string is secured to an end of the spindle which has a circumference of 25 mm to 35 mm. 
     
     
       6. A machine head as claimed in claim 5 in which the spindle has a hole adjacent the end to accommodate the string in securing thereof to the spindle. 
     
     
       7. A machine head as claimed in claim 6 in which the screw threaded adjustment means is carried by a plate which is adapted to be secured to a head of the instrument. 
     
     
       8. A machine head as claimed in claim 1 in which the spindle mounting means is a sleeve bearing in which the spindle is journalled. 
     
     
       9. A machine head as claimed in claim 1 in which the free end of the threaded member has a curved surface to engage the arm. 
     
     
       10. A machine head as claimed in claim 1 in which the arm is fixedly secured to the spindle. 
     
     
       11. A machine head as claimed in claim 1, wherein the threaded member is rectilinearly moveable along an axis offset with respect to the longitudinal axis of the spindle. 
     
     
       12. A machine head as claimed in claim 11, wherein the arm is located on one end of the spindle and the string is located on another end thereof. 
     
     
       13. A machine head as claimed in claim 1, wherein the arm is located on one end of the spindle and the string is located on another end thereof. 
     
     
       14. A machine head as claimed in claim 13 in which the another end of the spindle to which the string is secured has a circumference of 25 mm to 35 mm. 
     
     
       15. A machine head as claimed in claim 1 in which the spindle has a hole adjacent one end to accommodate the string in securing thereof to the spindle. 
     
     
       16. A machine head as claimed in claim 1 in which the screw threaded adjustment means is carried by a plate which is adapted to be secured to a head of the instrument. 
     
     
       17. A machine head as claimed in claim 16 in which the plate carries the spindle mounting means including a sleeve bearing in which the spindle is journalled. 
     
     
       18. A machine head for an instrument having a plurality of strings comprising: (a) a carrier adapted to be secured to the instrument; and   (b) a string tensioning device located on the carrier for each of the plurality of strings, each said string tensioning device comprising: (i) a spindle around which one respective string is passed and to which the respective string is secured, the spindle having a longitudinal axis;   (ii) means mounting the spindle for rotation about the longitudinal axis;   (iii) a single arm extending from the spindle; and   (iv) screw threaded adjusting means including a threaded member which threadingly engages an abutment and a free end which engages the arm, for displacing the arm and thereby rotating the spindle about the longitudinal axis to pull the respective string around the spindle and tension the respective string.     
     
     
       19. A machine head as claimed in claim 18, wherein, for each said string tensioning device, the threaded member is rectilinearly moveable along an axis offset with respect to the longitudinal axis of the spindle. 
     
     
       20. A machine head as claimed in claim 19, wherein, for each said string tensioning device, the arm is located on one end of the spindle and the string is located on another end thereof. 
     
     
       21. A machine head as claimed in claim 18, wherein, for each said string tensioning device, the arm is located on one end of the spindle and the string is located on another end thereof. 
     
     
       22. A machine head for fitting to a stringed instrument for tensioning and so tuning up a string, the machine head comprising: a spindle having a string attachment end around which the string is passed and to which the string is secured, the spindle having an adjustment end and a longitudinal axis;   means mounting the spindle for rotation about the longitudinal axis;   a single arm extending from the adjustment end of the spindle; and   screw threaded adjusting means for displacing the arm and thereby rotating the spindle about the longitudinal axis to pull the string around the spindle and tension the string, the screw threaded adjustment means including a threaded member which threadingly engages an abutment and a free end which engages the arm, when displacing the arm.